U.S. Pat. No. 7,610,934, that was filed by the applicant, describes an offshore transfer system comprising an articulated yoke mooring system having a first structure with a vertical first arm and a second arm and a damping mechanism acting on the second arm for damping movement of the second arm around the articulation joint between the two arms upon transition of the second arm from an operative position to an inoperative position after disconnecting the releasable connector from a second structure. In the present invention the damping device relates to a damping device counteracting motions due to roll, pitch and yaw on the mooring system when connected in the operative position.
The international patent application WO2007096019, discloses a system having a connection structure adapted to provide a connection between a floating structure, and a mooring structure having a turntable rotatable around a vertical axis of the mooring structure. A rigid arm assembly and a set of pendulums are located at one end of the connection structure. In this prior art, a damping system damps the swinging motion of the pendulums. The damping system comprises a tank having dimensions and containing a predetermined amount of liquid such that the liquid is adapted to move in the tank due to the swinging motion of the pendulum members. This results in a liquid wave or travelling water bullet providing slamming impact and inertia forces creating a tank reaction force that is counteracting the swinging motion of the pendulum members thereby causing damping of the swinging motion of the pendulum members.
However in this solution the damping is only efficient once the acceleration of the trapped fluid is sufficient. Further, using a sloshing force (water displacement due to wave propagation) and slamming forces as damping forces, results in large structural loads in the system. In fact, the forces created within the tank are huge and hence the system has to be robust enough to withstand repeated strong impacts. The sloshing tanks further have several response modes and can thus provoke spurious excitation. Another disadvantage of this known solution is that the water level in the tanks shall be low, so that large tank footprints are required.